Nonlinear Coupling and Propagation in Poly-Phenyl-Acetylene Optical Waveguides

We describe, in the present paper, the production and optical characterization of thin noncrystalline waveguiding films of the polar organic polymer poly-phenyl-acetylene. The nonlinear behavior of the grating coupling, due to the third order nonlinear susceptibility of the polymer, has been investigated. We have used laser sources, producing short pulses ((tau) equals 100 ps) at (lambda) equals 1.064 micrometers and ultrashort pulses ((tau) equals 1 ps) at (lambda) equals 610 nm, to study the change in the coupling efficiency with respect to the pulsed beam average input power. In the two cases, the changes are attributed respectively to a thermal and electronic nonlinearity of the refractive index. First theoretical modeling of the obtained data is given in the frame of the coupled mode approach to the nonlinear behavior.